Leonardo da Vinci studied the camera obscura as a visual projection device.
A camera obscura is a darkened chamber or box with a small aperture. Light from a scene passes through the opening and forms an inverted image on the opposite surface. Leonardo described and investigated this optical effect in his notebooks, using it to study vision, light, perspective, and the geometry of image formation.
The principle was known before Leonardo. Ancient writers, including Aristotle, had discussed images formed through small openings, and medieval scholars further explored the phenomenon. Leonardo’s importance lies in the detail and clarity of his observations, not in being the first person to discover the effect.
A camera obscura is an optical ancestor of the photographic camera, but it does not automatically create a permanent photograph. The image must be observed or manually recorded. It is also different from a telescope, which uses lenses or mirrors to magnify distant objects rather than projecting an inverted scene through a simple aperture.